Abradant material and process of its manufacture



Nov. 6, 1934. E. BARRINGER 1,980,151

ABRADANT MATERIAL AND PROCESS OF ITS MANUFACTURE I ori inal Filed Dec. 3, 1926 Ab Pa sLve DevL oe Binder Comprises PolybasLc Acid l ol yhydrLc Alcohol Resin Inventon Lawrence E Ba n'mger:

Hts Attorney.

Patented Nov. 6, 1934 UNITED STATES Pa'rim'r I ABBADANT MATERIAL AND PROCESS or I rrs MANUFACTURE Lawrence E.

signor to ration of New York Application December 3, 1926,

Bar-ringer, Schenectady, General Electric Company, a corpo- N. Y., as-

Serlal No. 152,486

Renewed September 8, 19

8 Claims.

' 10 cutting property. For example the binder must not clog or gum the abrading surface when the surface is subjected to frictional heating during use. The binder must retain its bonding strength at high temperatures so as not to permit frictional disintegration of the surface layer. For some abradants, as in sand paper, elasticity of the binder is desirable. For some abradants immunity to moisture is important. The binder h should not readily decompose or carbonize when heated.

' I have found resins of the polyhydric alcohol polybasic acid class to have the special physical properties required for binders in high grade abrasive materials. These resins not only but are able to withstand high temperatures without decomposition. They do not clog the surface layers of abradants made by their use as binders. My invention comprises both new abradant compositions and a new method of fabricating the same. The accompanying drawing illustrates in perspective one particular device embodying my invention.

In carrying out my invention a comminuted abrasive material, such as alundum, carborundum, emery, garnet, or the like is mixed with a suitable amount of polybasic acid-polyhydric alcohol resin of the. class described in Callahan Patents 1,108,329 and 1,108,330 of August 25, 1914. This class of resins will be referred to in the appended claims generally as alkyd resins. Alkyd resins include all those complexes resulting primarily from the inter-reaction of a polyhydric alcohol, such as glycerol, and a polybasic acid, such as phthalic anhydride.

Alkyd resins are convertible by heating from a fusible state (A-stage) to a very tough, hard, inert, and non-fusible state (C-stage). In'an intermediate state (B-stage) the resin is less insoftens somewhat when heated. The A-stage resin is readily soluble in cold acetone. The B- stage and C-stage resin can be rendered soluble by heating with a solvent at sufliciently ele- 66 vated temperatures.

possess a high degree of strength and elasticity ert. In the B-stage the resin will not fuse but.

Preferably but not necessarily the resin is' associated with a plasticizing agent, such for example, as indene, phate, diethyl phthalate, glycol diacetate, benzyl benzoate, triacetin, or the like.

The alkyd resin may be mixed with a suitable amount of plasticizing agent, say ten per cent, at any of its conversion stages, for example, the

, resin can be incorporated with a solvent by heating the resin, preferably inpowdered form, in contact with a solvent'to a sufliciently high temperature until the resin structure is altered and solution occurs. Enough of the liquid plasticizing agent should be removed from the resin to permit a solidified product to be obtained'or indene polymer, tricresyl phoselse a solid plasticizing agent may be used, such 7 as cumar, rosin, ester gum, a pitch, diphenyl or even a natural gum.

The resin binder may be incorporated with the abrasive material'in any suitable way so as to get a complete distribution of the resin throughout the mass. For example, the comminuted abrasive may be incorporated with a solution of the resin in a suitable solvent, such as acetone, or mixed solvents as acetone, alcohol and benzol or alcoholic solutions of ammonia. Complete admixture may be assured by stirring the mass, as for example, in a heated dough mixer. In other cases the comminuted abrasive may be mixed with liquefied resin in a suitable mixing device, preferably at an elevated temperature. By another method the solid resin is powdered, preferably to a fineness which will passthrough a 60 mesh screen, and then mixed with the abrasive. Any of the foregoing methods of mixing may be used. I do not wish to be limited to these particular methods for any procedure whereby the abrasive and resin particles are brought into intimate contact to form a thorough mixture is satisfactory for the purpose. When the mixture is to be used for coating cloth or paper, I prefer to first coat the paper with a Solutionof alkyd resin, then air dry until tacky, apply the grains of abrasive material and finally bake the whole until the grains are firmly set in the resinous coating. The proportion of resin to abrasive will vary with conditions but by way of example, I may state that I have used successfully '60 parts of abrasive, such as alundum, with 5 parts of a resin made from glycerol and phthalic anhydride.

The abrasive and resin mixture may be molded at about 150 0. preferably in steel molds. The molding mass is held at this tem- .perature for a few minutes, the exact time depending on the size of the mass and other conditions. I The molded objects may be cooled in the mold to about 75 C. Thereupon the molded pieces are discharged from the mold and the resin is fully polymerized without pressure namely a grinding'wheel- 1 has been illustrated 'asmountedon a shaft 2 for rotation, is strong, moisture-resistant, and can be used under severe service conditions without gumming or clogging of the surface. Apparently the local high temperatures produced at the cutting surface by irictionally-developed heat during use volatilize any resin which may tend to accumulate at the surface by the'wearing away of the abrasive material. In fact, this class of resins themselves have an abradant action on cutting tools and it appears that the presence of small amounts of resin at the surface does not appreciably lower the abrading or grinding effect of the abrasive material. v

In a divisional application, Serial No. 402,801, iiled Oct. 26, 1929, and assigned to the same assignee as the present invention I have made claimson a flexible sheet material coated with an alkyd resin in which particles of abrasive are embedded.

What I claim as new and desire to secure by Letters Patent 01 the United States, is:

'solvent at an elevated temperature, and there- -upo'n subjecting the molded article to a pro-' 1. A grindstone comprising a preponderant proportion of particles of abrasive and a lesser proportion of alkyd resin in a tough, hard, moisture-resistant, non-fusible state.

2. A grindstone comprising particles of abrasive, a binder of alkyd resin, and a plasticizing agent for said resin.

3. A grindstone comprising particles of abrasive material bonded with a glycerol-phthalate resin in the'iniusible, insoluble state. y

4. .The process of making an abradant which consists in molding a mixture 01' an abrasive. material with an alkyd resin associated with a longed heat treatment.

5. The process or making an abradant which consists in molding a mixture of an abrading material and an incompletely condensed glycerol-phthalate resin under pressure at a temperature of about 150 C. and thereupon heating without pressure other than atmospheric for about to 150 hours at a. temperature gradually rising from about C. to 190 C.

6. A grinding wheelcomprising particles of an abrasive material and an iniusible, insoluble resinous compound of glycerine and phthalic tion of particles of abrasive material, bonded together with an,alky'd resin in the intusible,

moisture-resistant state. a

LAWRENCE a. summons. 

